
.bordered {
  border-top: dotted 1px black;
  border-bottom: solid 2px black;
}
#menu a {
  color: #111;
  .bordered;
}

.post a {
  color: red;
  .bordered;
}

.clearfix {
  display: block;
  zoom: 1;

  &:after {
    content: " ";
    display: block;
    font-size: 0;
    height: 0;
    clear: both;
    visibility: hidden;
  }
}
#bundle {
  .button {
    display: block;
    border: 1px solid black;
    background-color: grey;
    &:hover {
      background-color: white
    }
  }
  .tab {  }
  .citation {  }
}
#header a {
  color: orange;
  #bundle > .button;
}

@var: red;

#page {
  @var: white;
  #header {
    color: @var; // white
  }
}
/* 一个注释块
style comment! */
@var: red;

// 这一行被注释掉了！
@var: white;